ConnMan

ConnMan is a command-line network manager designed for use with embedded devices and fast resolve times. It is modular through a plugin architecture, but has native DHCP and NTP support.

Related articles

Installation

Install the connman package. wpa_supplicant, bluez, and openvpn are optional dependencies required for Wi-Fi, Bluetooth, and VPN functionality respectively.

Before enabling connman.service, ensure any existing network configuration is disabled.

ConnMan comes with the connmanctl(1) CLI, there are various #Front-ends available.

Front-ends
  • cmst — Qt GUI for ConnMan.
https://github.com/andrew-bibb/cmst || cmstAUR
  • Econnman — Enlightenment desktop panel applet.
https://www.enlightenment.org || econnmanAUR
  • LXQt-Connman-Applet — LXQt desktop panel applet.
https://github.com/lxqt/lxqt-connman-applet || lxqt-connman-appletAUR

Usage

ConnMan comes with the command-line interface, see connmanctl(1). If you do not provide any commands starts as an interactive shell.

ConnMan automatically handles wired connections.

Enabling and disabling wifi

To check if wifi is enabled you can run and check for the line that says . To power the wifi on you can run or if you need to disable it you can run . Other ways to enable wifi could include using the Fn keys on the laptop to turn it on or running ip link set <interface> up.

Connecting to an open access point

To scan the network accepts simple names called technologies. To scan for nearby Wi-Fi networks:

$ connmanctl scan wifi

To list the available networks found after a scan run (example output):

To connect to an open network, use the second field beginning with :

$ connmanctl connect wifi_dc85de828967_4d6568657272696e_managed_none

You should now be connected to the network. Check using or .

Connecting to a protected access point

For protected access points you will need to provide some information to the ConnMan daemon, at the very least a password or a passphrase.

The commands in this section show how to run in interactive mode, it is required for running the command. To start interactive mode simply type: 

$ connmanctl

You then proceed almost as above, first scan for any Wi-Fi technologies:

connmanctl> scan wifi

To list services:

connmanctl> services

Now you need to register the agent to handle user requests. The command is:

connmanctl> agent on

You now need to connect to one of the protected services. To do this easily, just use tab completion for the wifi_ service. If you were connecting to OtherNET in the example above you would type:

connmanctl> connect wifi_dc85de828967_38303944616e69656c73_managed_psk

The agent will then ask you to provide any information the daemon needs to complete the connection. The information requested will vary depending on the type of network you are connecting to. The agent will also print additional data about the information it needs as shown in the example below.

Agent RequestInput wifi_dc85de828967_38303944616e69656c73_managed_psk
  Passphrase = [ Type=psk, Requirement=mandatory ]
  Passphrase?

Provide the information requested, in this example the passphrase, and then type:

connmanctl> quit

If the information you provided is correct you should now be connected to the protected access point.

Using iwd instead of wpa_supplicant

ConnMan can use to connect to wireless networks. The package which is available in community already supports using for connecting to wireless networks. As will start wpa_supplicant when it finds it, it is recommended to uninstall wpa_supplicant.

Note that ConnMan is probably unnecessary for IWD users, as IWD can handle its own network configuration, in which case should be stopped.

Currently the -i-option of seems to cause that the WiFi-interface gets hidden from .

Create the following service file which should cause to use to connect to wireless networks, regardless if wpa_supplicant is installed.

Then enable/start the service.

Advantage of using instead of wpa_supplicant is, that the ping times seem to be much more consistent and the connection seems to be more reliable.

Settings

Settings and profiles are automatically created for networks the user connects to often. They contain fields for the passphrase, essid and other information. Profile settings are stored in directories under by their service name. To view all network profiles run this command from root shell: 

# cat /var/lib/connman/*/settings

Technologies

Various hardware interfaces are referred to as Technologies by ConnMan.

To list available technologies run: 

$ connmanctl technologies

To get just the types by their name one can use this one liner:

$ connmanctl technologies | awk '/Type/ { print $NF }'

To interact with them one must refer to the technology by type. Technologies can be toggled on/off with: 

$ connmanctl enable technology_type

and:

$ connmanctl disable technology_type

For example to toggle off wifi:

$ connmanctl disable wifi

Tips and tricks

Avoid changing the hostname

By default, ConnMan changes the transient hostname (see ) on a per network basis. This can create problems with X authority: If ConnMan changes your hostname to something else than the one used to generate the xauth magic cookie, then it will become impossible to create new windows. Symptoms are error messages like No protocol specified and . Manually resetting the host name fixes this, but a permanent solution is to prevent ConnMan from changing your host name in the first place. This can be accomplished by adding the following to :

[General]
AllowHostnameUpdates=false

Make sure to restart the connman.service after changing this file.

For testing purposes it is recommended to watch the systemd journal and plug the network cable a few times to see the action.

Prefer ethernet to wireless

By default ConnMan does not prefer ethernet over wireless, which can lead to it deciding to stick with a slow wireless network even when ethernet is available. You can tell connman to prefer ethernet adding the following to :

[General]
PreferredTechnologies=ethernet,wifi

Exclusive connection

ConnMan allows you to be connected to both ethernet and wireless at the same time. This can be useful as it allows programs that established a connection over wifi to stay connected even after you connect to ethernet. But some people prefer to have only a single unambiguous connection active at a time. That behavior can be activated by adding the following to :

[General]
SingleConnectedTechnology=true

Connecting to eduroam (802.1X)

WPA2 Enterprise networks such as eduroam require a separate configuration file before connecting to the network. For example, create :

Restart and connman.service to connect to the new network.

For more information, see connman-service.config(5) and Wireless network configuration#eduroam.

Avoiding conflicts with local DNS server

If you are running a local DNS server, it will likely have problems binding to port 53 (TCP and/or UDP) after installing Connman. This is because Connman includes its own DNS proxy which also tries to bind to those ports. If you see log messages from BIND or dnsmasq like 

named[529]: could not listen on UDP socket: address in use

this could be the problem. To verify which application is listening on the ports, you can execute as root.

To fix this connmand can be started with the options or by overriding the systemd service file. Create the folder /etc/systemd/system/connman.service.d/ and add the file :

Make sure to reload the systemd daemon and restart the connman.service, and your DNS proxy, after adding this file.

/etc/resolv.conf

If you want to know the DNS servers received from DHCP while keeping a custom , then append to the above file (clear the lines if not needed). Now connman will write them to instead.

Blacklist interfaces

If something like Docker is creating virtual interfaces Connman may attempt to connect to one of these instead of your physical adapter if the connection drops. A simple way of avoiding this is to blacklist the interfaces you do not want to use. Connman will by default blacklist interfaces starting with , , virbr and ifb, so those need to be included in the new blacklist as well.

Blacklisting interface names is also useful to avoid a race condition where connman may access or before systemd/udev can change it to use a Predictable Network Interface Names like . Blacklisting the conventional (and unpredictable) interface prefixes makes connman wait until they are renamed.

If it does not already exist, create :

[General]
NetworkInterfaceBlacklist=vmnet,vboxnet,virbr,ifb,docker,veth,eth,wlan

Once connman.service has been restarted this will also hide all the interfaces from GUI tools like Econnman.

Troubleshooting

Error /net/connman/technology/wifi: Not supported

Currently, connman does not support scanning for WiFi networks with , at the moment this functionality is available with only (see ). To connect to wifi with iwd, enable/start and then either follow instructions in Iwd to connect to the wifi or you can also use any of the #Front-ends. In order to have Wifi Scanning support from within connman, install wpa_supplicant and then restart connman.service after you stop .

Error /net/connman/technology/wifi: No carrier

You have enabled your wifi with:

$ connmanctl enable wifi

If wireless scanning leads to above error, this may be due to an unresolved bug. If it does not resolve even though wireless preconditions are met, try again after disabling competing network managers and rebooting.

This may also simply be caused by the wireless interface being blocked by rfkill, which can occur after restarting wpa_supplicant. Use to check.

"Not registered", or "Method "Connect" with signature ... doesn't exist"

When issuing commands, you may see errors like the following:

From a prompt:

connmanctl> connect ''service_id''
Error /net/connman/service/''SSID'': Method "Connect" with signature "" on interface "net.connman.Service" doesn't exist

From the shell:

# connmanctl connect ''service_id''
Error /net/connman/service/''service_id'': Not registered

These errors are produced because the agent is not running. Start the agent from a prompt with , and try again.

Error Failed to set hostname/domainname

connman can failed to set hostname or domainname due to lack of .

You will need to edit connman.service (and other like , etc ...) to modify the line to add .

See under or for more details.

Unknown route on connection

A log entry for an unknown route appears each time a connect is done. For example: 

...
connmand[473]: wlp2s0 {add} route 82.165.8.211 gw 10.20.30.4 scope 0 <UNIVERSE>
connmand[473]: wlp2s0 {del} route 82.165.8.211 gw 10.20.30.4 scope 0 <UNIVERSE>
...

It likely is Connman performing a connectivity check to the ipv4.connman.net host (which resolves to the IP address at current). See the Connman README for more information on why and what - apart from the connecting IP - it transmits. This behaviour can be prevented by adding the following to :

[General]
EnableOnlineCheck=false

This setting will cause that the default device will not switch to ONLINE, but stay in READY state. However, the connection will still be functional.

The connection itself is also functional (unless behind a captive portal) if the check is blocked by a firewall rule: 

# ip6tables -A OUTPUT -d ipv6.connman.net -j REJECT
# iptables -A OUTPUT -d ipv4.connman.net,ipv6.connman.net -j REJECT

File /proc/net/pnp doesn't exist

If you see this in your error log it is caused by bug in connman and can be ignored. Bug Report

gollark: Yes, but nobody ever wanted or asked for that.
gollark: What do we want? Differently coloured Accept/Decline buttons! When do we want it? Now!
gollark: Also, the stupidly low-time AP is so very convenient.
gollark: Assuming the day thing is true, which it seems to be.
gollark: My egg is going to come out either blue or purple, because I got it later.

See also
This article is issued from Archlinux. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.